I have a 98 and my engine doesn't have the EGR and for the life of me I can't find a Snorkel. Should I be looking for something else.

Now the Air Intake Modification? What does that do for you? I have access to a machinist and can get that done real simple. Making it perfect, but is it worth it?

Now the FSD remote Cooler. I had mine replace about a year ago. But I don't have the remote cooler. Is it worth getting now or just wait until it gets cooked again.

Now I was also reading about pin # 1 - 9. Does the extra fuel make a difference when it's that small? How does it affect MPG?

Now I have some other things in the works. I would like to replace the Exhaust with 4" as it sounds like some have done. I heard that you can only fit a 3.5" on. Who is right? Being in NJ they like to see the CAT on. A large pipe and the CAT doesn't work. Do you just remove the CAT and forget about it. What about inspections?

If anyone can suggest anything else I should be thinking about let me know.

I use the truck mostly for going back and forth to work. In the summer it pulls a 4.5 ton Travel Trailer a couple of times a month. With a little over 120K miles on it I still have a lot of life left. I'm looking for this engine to out live me. Oil gets changed every 2500 miles and fuel filter gets changed every 5000 miles. Some of the best advice I got was that Oil is cheap. I got the truck at a 100K. Looks like the past owner took care of it. I already had the trans fluid and filter changed by a tranny guy. Wanted him to inspect it. He said everything was fine that I had a lot of life left there.

With access to a machinist you might consider having the upper plenum remade to a bigger diameter (2 1/2" -3") and tap in ports for the IAT and MAP sensors.

This has to be an improvement in grinding ther stock piece, which is the path well traveled.

3 1/2" is the biggest downpipe you can fit without removing some frame material.

Emissions inspection require you weld that cat back on the new pipe even if it does nothing.

I'm assuming your vin #8 is F which you won't have an EGR also snorkel is on early model trucks with exception of EGR stuff tips in FAQs /performance thread will benefit you

With access to a machinist you might consider having the upper plenum remade to a bigger diameter (2 1/2" -3") and tap in ports for the IAT and MAP sensors.Can you explain a little better here. For some reason I'm being thick at the moment. Making the Upper Plenum bigger is just what kennedy is showing in his tech tips right? So this will increase the air flow making the engine run cooler and better?

Now I was looking at the acronym decoder FAQ and when you talk about tapping the IAT & MAP You are taking adding the Gauges right. One for IAT for boost and MAP for exhaust?

The truck is a F and L65 if you haven't already decide on that.

Since we are talking mods and working on the engine. Where can I find a manuel(s) that would cover everything. Say I wanted to pull my engine or tranny I would have detail instructions.

www.helminc.com GM official manual site can also be found on ebay and old book sellers

If I remember right. The drivers side Manifold comes down uses the crossover and connects with the passager side manifold. Then the down pipe comes from there. So a 3.5 is the only pipe that fits. If I increase from the down pipe to a 4 or even a 5 that would be a improvement.

The last I time I looked at the crossover and manifolds the ID was only around A 3" at most. As long as I don't restrict the flow back down smaller than what's in front it should be an improvement. I just wonder if the run from the front to the back would accept such a large pipe? How about back pressure? Do you think this would give me codes.

The upper plenum or snorkel that jk shows ported in his tips section is quite restrictive. It goes from 2 1/2" down to a thin flat squished portion. I'm suggesting replacing the entire snorkel with a custom made unit that doesn't flatten out. Grape made a nice looking unit with a piece of plate and a 90* mandrel bent 3" pipe but he didn't have a MAP or IAT to think about.

QM his 97 doesn't have the inner fender snorkel

QM know I understand what you are saying. Makes me wonder with the sensors it would throw some codes opening up that much air flow. I would need to talk to my machinist about this. Making the part and remounting the sensors wouldn't be a problem it's doing all that work and then having engine codes. I also wonder if they want the air flow to get restricted at this point to build pressure to force the air down. Having that much of a cavity might defeat the purpose.

QM his 97 doesn't have the inner fender snorkel
I'm talking about the aluminum upper plenum(snorkel) that most people tap for their boost gauge as you and I have.

Opening that area isn't going to set off any codes. Pressure will build as it did before just won't build as fast or as high.

The snorkel is the plastic duct inside the fender it is not the upper plenum itself. With an "f" plenum there is not as much material to remove as the "s" besides a little porting of the feed in. Heres the pic from Kennedy's website of the snorkel.
http://www.kennedydiesel.com/images/Snorkels.jpg

I shot some pics of a F upper I'll be installing in about 3 K miles when extended warranty goes out maybe you can explain your point. QM I don't get what you are saying, other than belling out the inlet tube not a whole lot of meat to do any other grinding mods without putting casting at risk. I have some pics of a modded S intake in my IC install page in my sig.

TD-- the lower plenum on our "s" trucks has the pipe in the middle to feed the egr. how are you going to block this off? i replaced the upper and lower intakes with an "f" setup, it has no egr feed. heres a pic of whats inside the "s" lower again from Kennedy's site.
http://www.kennedydiesel.com/images/EGR-mystery-gasket.gif

TD,

If I'm right QM was saying that instead of having a round tube get smaller and open into the flat part. Like what your 4th pic is showing. Make that square part of the housing larger so that the tube part goes into it full size.

Tube goes into a fat box in stead of a flat box.

That transition is really what you want. It helps to fill the plenum with less turbulence...

No, RJ
What I'd like is a greater volume in transition above the lower plenum bowl. Even bigger than what grape has pictured below.



a picture of his homemade upper plenum.
http://www.imagestation.com/picture/sraid148/p76c22efba292330fceeb06e5507ba1b1/f61de7a9.jpg
Man, this is beautiful. BTW, I think grape's 6.5L here will be a monster.
http://dieselplace.com/forum/uploads/1B2_Mvc-005s.jpg

Here's a plate I cut out a year ago to give me a feel for the upper plenum's dimensions. If you've ever looked at the intake member on a cummins that's what it might slightly resemble.

As the newer plenum comes in from the side it would be more boxy. Instead of being flat like it is now. What a 3.5" or 4" box height.

Grapes currently comes down from the top from the pic.

It comes from the drivers'side because his IC return hose comes from there.

I'm sorry, but the unit pictured and attributed to Grape will have much higher exit losses when it comes out of the round tube into the plenum. The stock unit will likely flow better.

There has to be a reason why it flattens out instead of staying wide. I wonder what the engineers where thinking. Looks like they did it to have the flow go over the entire top.

Was it space and material saving?

Or are the aerodynamics involved?

...Or are the aerodynamics involved?
A better term would be fluid dynamics, but yes. Aerodynamics is typically used to describe vehicles moving through the air or components that are used to do work on air (blades, vanes, propellers, etc.)

Fluid flow hates sudden changes in flow area. It likes smooth transitions designed to keep the boundary layer from separating. The shape of the inlet was designed to spread the airflow out to better fill the plenum with minimal boundary layer separation. The height of the passage was selected based on the desired width (to match the plenum width) and equivalent flow area (with some fudge for Reynolds number effects, I'm sure) to the round inlet tube.

Ah grasshopper the F lower that I have and also will be installing won't have that problem no MO, been chomping at the bit for year and a half for extended warranty to run out to convert 100% F engine in only a 6400# K1500 will doing 18:1 build plus some other things then also. I don't suspect MS getting real excited about that kind of conversion any time soon.

TD-- the lower plenum on our "s" trucks has the pipe in the middle to feed the egr. how are you going to block this off? i replaced the upper and lower intakes with an "f" setup, it has no egr feed.

grasshoppa must have barance or he hop sideways

Sorry for cutting in guys, but I was wondering about that plastic snorkel in the fender. My truck is a 1995 L56 and just a little while ago, I decided to follow Kennedy's airbox modification. When I unscrewed the plastic unit (that holds the filter and the "cone") from the wheel well and looked through the hole into the fender, was I supposed to see that snorkel there? I stuck my hand in there and there was only bare metal all around.

Then it's not there.

A better term would be fluid dynamics, but yes. Aerodynamics is typically used to describe vehicles moving through the air or components that are used to do work on air (blades, vanes, propellers, etc.)

Fluid flow hates sudden changes in flow area. It likes smooth transitions designed to keep the boundary layer from separating. The shape of the inlet was designed to spread the airflow out to better fill the plenum with minimal boundary layer separation. The height of the passage was selected based on the desired width (to match the plenum width) and equivalent flow area (with some fudge for Reynolds number effects, I'm sure) to the round inlet tube.
OR So the height was selected to solve or not cause clearance issues.

Yes fliud or air in this case likes smooth changes in flow area. The decreasing area will act to speed up the air flow as you force the same air into a smaller area and therefore reshape and turn it downward to enter the engine. I believe that a "better" redesigned area could be a positive change.

WOW, that engine was sweet, id like to have that settin in my truck:ro)

No kiddin!! Beautiful looking engine :drool: I was hoping to hear that QM. I just found it strange because I understood that those snorkels were put in all 95' and earlier I believe.

I'm very taken with than pretty red engine. I'm going to have to think about painting my heads or something real soon.

So if we keep the same basic design and just increase the height so that the plenum opens into a larger area would we see an increase in performance or decrease? Or would we not notice anything?

How about if you couple the improved transition with a bigger turbo to fill that volume. I understand RJ's points but I don't think you have to sqeeze the air at the end of the plenum like that and If you increase the diameter of the inlet to 3"-4" the ratio of diameter to transition can stay close.

Now the FSD remote Cooler. I had mine replace about a year ago. But I don't have the remote cooler. Is it worth getting now or just wait until it gets cooked again.

Now I was also reading about pin # 1 - 9. Does the extra fuel make a difference when it's that small? How does it affect MPG?Does anyone have an opnion on these two questions?

Get the cooler but remote mount it away from the engine heat. Mine's in front of the radiator.

The higher number resistors increase the energized time for the FSD and may wear it out faster but each resistor increases fuel output 1/3mm3.

Going to the larger Turbo would make sense. This would be a fun mod to try. Getting the piece machined out isn't a problem. The machinist is family. Its the cost of the block of steel or aluminum & larger turbo thats the stopper. Plus I'm just starting on the basic mods for my truck.

Get the cooler but remote mount it away from the engine heat. Mine's in front of the radiator.

The higher number resistors increase the energized time for the FSD and may wear it out faster but each resistor increases fuel output 1/3mm3.

But does that small increase in fuel translate into anything noticeable? More fuel = more power & heat.

I would add recommendation of giving Bill Heath a call the 7yr warranty on his FSD is very attractive, not that the other methods aren't worthy but if it fails again you have to eat the cost of the replacement.

7 year warrenty?:eek: That does make it very tempting. At the cost of these units thats nice to have. With the way they fail they have to be making then by the ton. You would think they be cheap. Most likely cost $10 to make and then they sell for a fortune since you are screwwed with out it.

OR So the height was selected to solve or not cause clearance issues.

Yes fliud or air in this case likes smooth changes in flow area. The decreasing area will act to speed up the air flow as you force the same air into a smaller area and therefore reshape and turn it downward to enter the engine. I believe that a "better" redesigned area could be a positive change.The cross sectional area at the entrance to the plenum is 4.469 in^2. The cross sectional area of the tube is 3.142 in^2. As I said, the flow area was increased. This increase is more than would have been necessary for Reynolds number effects, so it is actually being used to slow the air flow down before dumping into the plenum. Again, to reduce losses.

The airflow is not being squeezed at all, as is being discussed. The shape is being changed and it is being expanded. All goodness for reducing inlet loss.

The factory inlet is better than the one shown in the image.

The cross sectional area at the entrance to the plenum is 4.469 in^2. The cross sectional area of the tube is 3.142 in^2. As I said, the flow area was increased.

Could you show how did you arive to those numbers? I can see the entrance of the plenum being ~4.5 in2, but the surface of the tube cross-cut has to be larger than that.

The exit opening at the plenum is roughly 5.5" X 13/16". That comes out to 4.469 in^2. The tube is 2" ID. (PI X 2^2)/4 = 3.142 in^2.

Now increase innerdiameter to 3" or 3 1/2". Here's an old cummins inlet btwhttp://i13.ebayimg.com/02/i/03/83/2a/7d_1_b.JPG

Won't do much good if the turbo compressor outlet is only 2".

That Cummins inlet is not good for comparison. The piece that it bolts to is not any larger in area than the exit there. There is some transition in the piece, but the main transition and main plenum is in the manifold after the splitline from the piece shown.

The late nacherly aspirated 6.5 gets an upper plemum almost the spittin' image of 'at sucker - same bolt pattern as turbo, is rotatable - check it out on Pen Diesel site.....................:cool:

I've seen one like it. I looked at a 6.2L with an ATS aftermarket turbo on it and it had a two piece circular upper plenum that was huge compared to the 6.5L upper plenum.

The cummins H1C has a 2 1/2" outlet. I bid on one of them and one garret style.

www.helminc.com (http://www.helminc.com/) GM official manual site can also be found on ebay and old book sellers
I also order the complete service manual. Talk about paying through the nose. Censored Censored

But it will be worth it the first time I need it.

Really?? I just ordered the whole 1994 set for $90 from helm. Some sale that I read about on here.

I also order the complete service manual. Talk about paying through the nose. Censored Censored

But it will be worth it the first time I need it.

Mine came out to $142 with tax and shipping. I just order today. When did you order?

I got the entire 6.5 set. Came in after I typed that last post. I just looked. It was a sale on 95 and earlier. Sorry man.

DOH!

Actually they will pay for themselves, dealers don't keep up to date on the "old 6.5" 1st time you have to take one to a dealer if it's too much you feel like messing with, you will know when they are trying to BS you and have something now to keep them honest.

If the information in this forum we're organized into a consice document, it would be a vital supplement to any service manual. There's plenty the manuals are vague on.